Scale-type apron for headboxes



July 23, 1968 w. N. BENNETT SCALETYPE APRON FOR HEADBOXES Filed Aug. 4, 1965 5&2. 3.1:: 1:95.555. 1

INVENTOR WILLIAM N. BENNETT ATTORNEY a es FIG. 3

United States Patent 3,394,048 SCALE-TYPE APRQN FOR HEADBOXES William N. Bennett, Fitchhurg, Mass, assignor to Fitchburg Paper Company, Fitchburg, Mass., a corporation of Delaware Continuation-in-part of application Ser. No. 299,659,

Aug. 2, 1963. This application Aug. 4, 1965, Ser.

7 Claims. (Cl. 162343) ABSTRACT OF THE DISCLOSURE The apron leading from the headbox slice onto the Fourdrinier wire of a conventional paper making machine is fabricated of thin stock and so as to include a repetitive pattern of protuberances each providing a separate drop-off edge facing the down stream direction of stock flow. The sheet is supported on top of a honeycomb construction and a beveled edge is attached thereto leading in the downstream direction.

This invention relates to my copending application Ser. No. 299,659 filed Aug. 2, 1963 and now U.S. Patent 3,269,892 of Aug. 30, 1966. In general the invention relates to improvements providing uniform fiber distribu tion in paper pulp stock as it flows on an apron from the headbox through the slice onto the Fourdrinier wire, and this is accomplished by the provision of a series of repetitive scale patterns forming projections on the apron where each projection has an edge extending upwardly or away from the surface of the supporting member for the stock, the edges breaking the surface tension of the flowing stock with relation to the supporting surface, causing the stock to flow in relatively small crossing streams uniformly throughout the surface of the slice or apron, criss-crossing the fibers.

In the particular invention herein new and improved means is provided for maintaining the apron perfectly straight and rigid across the entire machine. Some machines are very wide and it is almost impossible to maintain the apron level across the machine, particularly at the point or edge where the pulp stock flows onto the Fourdrinier wire. Clearly these aprons tend to bow downwardly in the middle and this of course results in a much deeper flow of pulp at the center portion than at the edges, and this variation extends from the extreme edges of the wire to the center thereof, being of course deepest at the center.

Therefore the present invention has for its main object to provide a scale-like formation as described in my previous application above identified but which will not bend or sag across the wire and this is accomplished by the use of a vertical or right angle honeycomb construction firmly secured to a plate upon which the scales or other similar protuberances appear, forming an upper layer; in combination with a plain bottom lamination at the opposite side of the honeycomb construction, so that with these three parts firmly adhered, there can be no deflection of the assembly or laminated structure across even the widest sheet since such deflection must result in destruction of the honeycomb before the bottom plain layer can flex due to the fact that the honeycomb structure is secured at an almost infinite number of places in a continuous manner across the bottom lamination, and of course the same is true as to the connection between the honeycomb construction and the sheet hearing the protuberances.

Other objects and advantages of the invention will appear hereinafter.

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Reference is to be had to the accompanying drawings in which:

FIG. 1 is a view partly in section illustrating a headbox and the location of the novel apron with relation to the Fourdrinier wire;

FIG. 2 is a sectional view through the new apron on a greatly enlarged scale, and

FIG. 3 is a plan view thereof looking in the direction of arrow 3 in FIG. 1.

This invention has been illustrated as applied to a more or less conventional headbox having a pipe 10 through which the stock flows into the headbox with the fitting 12 as usual, a partition 14 over which the stock flows at the edge 16, thence downwardly into the space between an inclined wall 14 and a partition 18, the latter terminating above the bottom of the box for the flow of the stock thereunder and thence upwardly over the wall 20 and onto the slice indicated at 22. Any other headbox can be used also. The new apron is illustrated in general by the reference numeral 24 and the pulp flows down the slice and onto the apron 24 to the Fourdrinier wire 26, the breast roll being illustrated at 28. The new apron can also be used in other relations where it may be found desirable.

Referring now to FIG. 2, there is shown here the cross sectional view of the apron 24. The bottom member thereof is a very thin plain sheet member 30 which is conveniently made of suitable metal or plastic or the like, and which is permanently secured as by adesive for instance to a foil or the like honeycomb construction 32. This honeycomb construction is of itself not novel and it is believed that it need not be further described except that it is of substantial length compared to the width of the member 30 and is formed in hexagonal continuous shapes completely throughout the entire apron.

At its upper end the honeycomb structure 32 is permanently secured with respect to a single sheet 34 upon which appears a series of protuberances which in this case appear in a single formed sheet. They appear in general like shingles which have curved edges as shown at 36 in FIG. 3. This sheet may be made of rubber, plastic, or metal, and is conveniently formed in any way such as by die rolling or the like, but the point is that the sheet 34 having the protuberances thereon is a continuous sheet having a smooth plane bottom surface indicated at 38 in FIG. 2 which is adhesivel-y secured to the upper edge surface of the honeycomb construction at the lower edge surface of which is secured the plain sheet 30.

It has been found that no matter how wide the machine, a construction of this nature is virtually incapable of deflection and therefore it is pointed out. that not only is the even distribution of the pulp flow obained as explained in my copending application above identified, but also an even amount of pulp is flowed onto the Fourdrinier wire completely across the machine.

The general effect of this is of course that the pulp is uniform as it moves onto the Fourdrinier wire so that not only are the fibers criss-crossed and distributed in an even and uniform manner throughout the stock as it moves onto the wire, but also the depth of the stock is made even from side to side of the machine.

The forward or downstream edge of the construction may be provided with a beveled flow edge at 40 if desired, as the honeycomb structure is rather thick.

Having thus described my invention and the advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what I claim is:

1. Apparatus for the uniform distribution of the fibers in the paper pulp stock of a paper making machine comprising a stiff and rigid structure over which the stock flows, said structure comprising three parts, an upper sheet-like member provided with a repetitive pattern of protuberances each providing a separate drop-ofi edge facing the downstream direction of flow of the stock, a second member secured thereto and comprising a honeycomb type of continuous construction of extremely lightweight material including walls extending at generally normal to the first-named sheet, and a bottom substantially plain sheet-like member permanently secured to the opposite edges of the honeycomb construction from the first-named sheet-like member.

2. The apparatus recited in claim 8 wherein the said drop-off edges are aligned in rows across the first-named member, adjacent rows being staggered with respect to the edges of each row.

3. The apparatus recited in claim 8 wherein each of said protuberances is inclined on its top surface from a maximum at the drop-01f edge thereof to a minimum adjacent the honeycomb construction.

4. The apparatus of claim 9 wherein the drop-off edges of the protuberances extend in part across the stream and in part generally at angles to the direction of the stream.

5. The apparatus of claim 9 wherein the drop-off edges of the protuberances extend in part across the stream and in part generally at angles to the direction of the stream in staggered rows.

6. Apparatus for the uniform distribution of the fibers in the paper pulp stock of a paper making machine comprising a stiff and rigid structure over which the stock flows, said structure comprising three parts, an upper sheet-like member provided with a repetitive pattern of protuberances each providing a separate drop-01f edge facing the downstream direction of flow of the stock, a second member secured thereto and comprising a honeycomb type of continuous construction of extremely lightweight material including walls extending at generally normal to the first-named sheet, and a bottom substantially plain sheet-like member permanently secured to the opposite edges of the honeycomb construction from the first-named sheet-like member, and a beveled edge member secured to said first-named member along the downstream edge thereof.

7. Apparatus for evenly distributing a flowing stream comprising a stiff, rigid coplanar apron over which the stream flows, said apon including three main parts in a laminated form,

one part comprising a sheet of material including a repetitive pattern on its upper surface of a series of protuberances each having a separate downstream drop-off edge,

a second part comprising a plurality of interconnected walls forming enclosed chambers, the walls being substantially at right angles to the plane of the first part and secured thereto at the lower surface thereof.

a third part comprising a plane sheet of material at the opposite side of the second part from the first part and secured to the walls of the second part,

the first and third parts being parallel and relatively thin, the second part forming a relatively thicker structure which extends substantially throughout the areas of the first and second parts parallel thereto; and

a beveled edge member extending in the downstream direction from said apron.

References Cited UNITED STATES PATENTS 5/1964 Watter 16168 8/1966 Bennet 162--343 

